Resistance-based random access memory devices use a variable resistive material to store data. The variable resistive material has a resistance that can be changed responsive to a programming voltage. For example, a storage element of a resistance-based random access memory device may be programmed to a first resistance state to indicate storage of a first logical value (e.g., a “0” value) and may be programmed to a second resistance state to indicate storage of a second logical value (e.g., a “1” value).
Storage elements of a resistance-based random access memory device can be arranged in a three-dimensional structure. In such a structure, each storage element may be placed between a bitline and wordline. For example, a first storage element may be coupled to a first bitline and a first wordline. A second storage element may be coupled to the first bitline and a second wordline. Another storage element may be coupled to a second bitline and the first wordline. In this arrangement, to read the first storage element, a read voltage may be applied across the first storage element by applying a first voltage (e.g., a relatively high voltage) to the first bitline and applying a different voltage (e.g., a relatively low voltage) to the first wordline. A sense amplifier coupled to the first bitline may sense current that flows through the first bitline. The current flowing through the first bitline may correspond to current that flows through the first storage element responsive to the voltage across the first storage element. Thus, the current can be used to determine a resistance state of the first storage element using Ohm's law.
Since the storage elements of the resistance-based random access memory device store logical values based on resistance state, different read currents are used to read different logical values. For example, reading a storage element that is in a low resistance state uses more read current than reading a storage element that is in a high resistance state.